It is a well-accepted fact that dental plaque when allowed to accumulate on tooth surfaces can eventually lead to gingivitis, periodontal disease, caries and calculus. Thus, it is apparent that effective removal of deposits of dental plaque is absolutely essential for oral health. Accordingly, a proper oral hygiene practice which may be carried out by an individual on his or her own teeth or by a dentist, necessitates readily available means of identification and location of plaque deposits in the oral cavity. Since dental plaque is usually transparent and colorless and not easily visible, an individual frequently is not aware of the quantity or the location of dental plaque present in the mouth.
The prior art includes various dentifrices for removing plaque, including dentifricating paste, powders, and microbial liquids. As a general matter, these dentrifices contain a mixture of various ingredients including such materials as polishing agents and abrasives for scouring and scrubbing the teeth, and which are further operable, to some degree, to neutralize various acids present in the gaps between the teeth. These same substances further inhibit, to some extent, the subsequent growth of various forms of bacteria that contribute to the development of caries and other disorders. While the prior art dentifrices have varying degrees of success, they have not been successful in arresting decalcification and other diseases which are exasperated by the use of braces.
The amount of decalcification and tooth decay found in orthodontic patients, in fact, is alarming. Numerous studies have been conducted showing the severity of this problem in the orthodontic patient population. Each year, half of the three to five million yearly patients who get braces in the United States suffer from early tooth decay.
Accordingly, dye indicators for dental plaque as a means of measuring tooth cleanliness and to effect proper oral hygiene practices, have been widely explored in the prior art.
U.S. publication 2007 0237726 ('726 publication”) teaches plaque disclosing products containing coloring agents or pigments that are absorbed by the plaque and render it visible. According to the '726 publication: “Most plaque disclosing compositions are based on colorants such as disclosed in U.S. Pat. Nos. 3,309,274; 3,624,219; 3,997,658; 4,302,439; 4,459,277; 4,517,172; 4,590,061; 4,666,700; 4,992,256; 5,098,691; 5,190,743; 7,182,935. Examples include synthetic organic colorants such as, amongst others, erythrosin (FD&C Red #3), Allura Red (FD&C Red #40), Green #8, Red #19, Red #22, Red #28, fluorescein (Yellow #7) and fluorescein disodium salt (Yellow #8).
The 726 publication teaches that natural colorants have been used as plaque disclosing agents, including a red dye extracted from sugar beet, a salt of sanguinarine, and cobalamin compounds, particularly cyanobalamin (Vitamin B12). According to the '726 publication, some of these colorants are invisible to the human eye in normal daylight or artificial light and may require the use of light of a particular wavelength to become visible.
U.S. Pat. No. 7,182,935 also discloses that natural colorants have been suggested as alternatives to the use of synthetic organic colorants as plaque disclosing agents. According to the '935 patent, artificial colorants have disadvantages which natural colorants do not present. “Some artificial colorants provoke diseases of the thyroid, lesions of the liver, hyperacidity and allergies such as, for example, asthma, rhinitis and rashes.”
According to the '935 patent, examples of natural colorants used to disclose bacterial plaque are taught in U.S. Pat. No. 4,431,628 and U.S. Pat. No. 4,517,172. “The U.S. Pat. No. 4,431,628 refers to a method for indicating the presence of bacterial plaque, comprising an efficient quantity of natural colorant extracted from sugar beet. . . . U.S. Pat. No. 4,517,172 describes a method for the visualization of plaque, in such a manner that the plaque is visible to the naked eye under ultraviolet light. The method employs a salt of sanguinarine precipitated from extracts of plants selected from the group consisting of Sanguinaria canadensis, Macleaya cordata, Corydalis sevctvozii, C. ledebouni, Chelidonium majus and mixtures of these.”
The '935 patent itself is directed to a disclosing agent based on natural colorants comprising at least one concentrated solution of natural colorant selected from the group consisting of colorants extracted from the aai (Euterpe oleracea) and colorants extracted from urucum seeds (also known as Annatto seeds) of the plant Bixa orellana. 
It is believed that none of these prior art natural colorants have been commercially successful. It is believed that the reason for the lack of success is that these coloring agents are not visible enough, concentrated enough, appealing visually, and/or stable enough to comprise an effective product. It would be desirable to have a colorant that can be used safely and effectively in a dentifrice identifying plaque without the need for a UV light source.